GM LS1 for marine use

I'm gonna look seriously into a sbc now, but there's just something about that ls1, it's so pretty... I'm just gonna run a standard wet system, and try to find an engine dyno to rent or buy that I can use to tune the ecm with. Still undecided on an LS1 or a sbc with an aftermarket efi kit. Losing the o2 sensors uncomplicates things alot. I can run the GM LS1 ecm in open loop and just program it accordingly. I don't think there would really be that much more cost to go with the LS1. The parts may not be as readily available(starter, manifolds, etc...) but I don't think it will be that bad. I see a couple of low mileage LS1's on ebay for < $3000. Anything I buy used will see a trip to the machine shop just to check everything out. I'll probably have as much of it powder coated as I can while it's taken apart.

If I go with the 350, I'll probably use one of the LT1's I had a couple and liked the gear-drive water pump, it saved me a couple of times. There's a few things that I would correct though, such as that pseudo-distributor piece of crap or whatever it is and shove it where the sun don't shine. Who puts a piece of electronics directly below the weep hole of the water pump? That thing almost gave me more trouble than the cooling system. I played hell keeping the thing from overheating. I'll try to find some way to lower the compression and convert it to a standard flow cooling system. That reverse flow system would freak out if even the slightest bit of air was in the system.

The current props are 14x14's. I bought them off ebay so I'm not really really sure they're 14x14, but that's what they were marked and sold as. It had 14x10 when I bought it. At 2500 rpm and nobody on board, the 14x10's moved me along at around 17mph, with a top speed of about 27 at 5000rpm. The engines would rev well over 6000 rpm with those props, so it was seriously underpropped. With the 14x14's, I got 22@2500rpm, and 26@3500rpm. Any more than 3500rpm and they started vibrating wildly, I don't know if it is a cavitation problem or a balance problem. The fuel economy seemed to drop from about 1.1mpg with the 14x10's to about .7mpg with the 14x14's. Now I can only get around 20@3500rpm thanks to the coral reef that's now growing on the bottom of the boat.

I intend to put at least 1.5:1 if not 2:1 transmissions in. The extra torque will warrant replacing the 1" shafts with something a little bigger, but hopefully it'll increase the efficiency of the props. I don't think most of them were designed to spin 5000+ rpm.

 

I am not thrilled with all you wrote. First off 1:1 is ok for an inboard. 1.5:1 is ok too but 2:1 is too much for that light boat. Proper props make all the diffference in the world.
As far as the LT1 and gear drive water pump, what are you gonna do on the reverse rotation engine? A standard SBC would use off the shelf parts for your marine app. If you didn't need to control timing there is even a stand mallory unilite distributor for marine use. 325-350 HP is pretty easy to reach with a standard 350.
Here is an off the shelf marine engine making 320 HP http://www.mercruiser.com/mx_6.2_mpi_horizon_ib_-_320_hp
You really need to talk to a prop guy and find out what performance you will get from what prop,HP and gear reduction in that particular hull.

 

If you use VolvoPenta outdrives, they turn either way; so do Twin Disc transmissions.

 

the O2 sensor thing I find rather amusing.

are there no boats left out there these days which dump thier waste gases into the atmosphere ? What's wrong with dry exhausts ??

 

Dry exhausts heat up the engine room and are a fire hazard. What is amusing about it?

 

ok... a clarification... I find it amusing that no-one seems to want to consider putting thier exhaust topside and eliminating the 02 sensor hassle. We only really use the water as a muffler...

 

How amusing is it to have a boat without a useable cockpit. You couldn't fish or ski or lounge. Do you boat?

 

I boat...

I used to co-pilot/observe for a ski race boat. Not for too long though.. seeing a guy all but pull his arm off kinda spoiled it for me.

I guess it depends on your concept of 'useable' I guess. There are quite a few ski boats around here on the river with pipes which basically come straight up and out into a pair of mufflers and they are not dedicated race boats.

some people are spoiled with all the mod cons..

I dont intend to run the pipes out into the water on my boat. I'm going to run a largish collector and muffler and I'm not overly concerned with noise, not that it's likely to be an issue. I can get stainless truck mufflers for suprisingly little, so the only water I'm likely to have any problems with, is rain, which is fixed easily enough.

I'm also one of these guys whom doesnt like puncturing his hull for any reason that isnt totally and utterly neccessary.

 

How does that answer Daniel2's question? He needs a wet exhaust for his application.

 

self importance ? man-o-man, I'm sorry, I'm obviously used to a much more relaxed board. I'll remember to remain precisely on topic from now on.

Incidentally, how does suggesting a 350 stay on topic ?

The LS1 motor is good, but according to the local engine re-conditioning shop, its a very hit and miss sort of motor. You can get absolute gems, and some real turkeys. The actual LS-1 design is excellent. Evidently the quality control wasnt that brilliant, lots of tolerances are often very close to out of spec, some with crank misalignments of 3 thou or more, requiring some pretty serious honing to bring them back into true. Then there's cases of bores varying by as much as 6 thou accross one engine and consequent oil holding issues. Basically, the guys tuning LS1's these days, as a matter of course, go right through them and 'blueprint' them, ( in the old parlance), to make sure everything is as it should be. if Daniel buys some, it would be best to do the above. Go through and check every tolerance, even if he doesn't rebuild them.

As far as the 02 sensor goes, a tough thing to fix, unless he likes the idea going truck style like me.. If you got it... you may as well flaunt it.. or, fit catalytic converters and go quiet. I'm not familiar with his actual boat so forgive me if I'm suggesting something really silly.

 

I didn't read all the replies, so if someone covered this, sorry.

why use counter-rotating engines? Use the transmissions to handle that; run one in A position, and the other in B. Much, much easier

 

saeble: sorry if I offended you. Are your truck engines in Australia set to run without O2 sensors?

 

no probs Gonzo

no, we run O2 sensors, the point is that if you run your exhaust up into the air, you solve the wet/cool exhaust problem

 

ls1

ok guys, we have invented this wheel long ago..

go here http://www.waspaust.co.nz/

all manifolds, brackets etc etc are avaliable off the shelf and at aussie and new zealand pricing it will be a bargain for you...

we also fit lexus V8's which cost $650nzd!!!

matthew@nzjetboating.com

 

looks like my idea of 'bargain' and yours are a little different

I looked at the Wasp stuff and whilst it looks to be absolutely top shelf stuff, its still comparitively expensive to the things that I'm envisaging. no diss to you, nor to the guys at Wasp. I just like to do things my own way and in a way that's really cheap and cheerful.

Put it this way, I have friends with $25,000 cars. Mine cost me $1200. In alot of ways, mine is superior to thiers and... I think I've locked it three times in all the time I've owned it, all the while watching the aforementioned friends sweating bullets over parking thiers in a supermarket car park. My insurance policy is weeny. I don't throw a massive tantrum if someone has the misfortune of scratching it. I haven't invested 40-50% of my income in my car. I don't believe I've got any ulcers and I can put most of my thinning hair down to genetics rather than worrying about my car/boat.

A whole lot of this world is about perspective. You dont have to spend a gazzillion bucks and have every last gadget known to man to be happy... if you sit down and really ask yourself 'do I need this in my boat/car ?' Nine times out of ten it comes down to some form of boat/***** envy issue which makes you want to have something with more stuff than the other guy.

That's something I'll never buy into.